Engineering functional doubly porous PHEMA-based materials

Functional doubly porous polymeric materials based on cross-linked poly(2-hydroxyethyl methacrylate) (PHEMA) were engineered via novel porogen templating methodologies. Two straightforward and versatile strategies were implemented through the use of either CaCO3 microparticles or poly(methyl methacrylate) beads as macroporogens, in conjunction with either hydroxyapatite nanoparticles of around 200 nm average diameter or a porogenic solvent (e.g., ethanol) as nanoporogens. Upon porogen removal, macropores with dimensions in the 100 μm range were generated, while the second porosity lied within the 1 μm order of magnitude, as evidenced by mercury intrusion porosimetry and scanning electron microscopy. The possibility to further functionalize such biporous PHEMA-based frameworks was investigated through a two-step synthetic approach involving an activation stage, followed by the coupling of propargylamine as a model compound. The success of the functionalization procedure was clearly demonstrated by Raman spectroscopy that indicated the occurrence of alkyne functionality within the biporous materials.